The invention relates to a novel diagnostic means and method of testing for pregnancy in humans, and to a test kit incorporating such diagnostic means and ancillary materials.
It has been known for some time that the presence of human chorionic gonadotropin (HCG) of placenta origin in the urine constitutes one of the early indications of pregnancy. Originally, in vivo methods for determining the presence of such HCG were developed, and while consistently accurate they have proved to be unwieldy because of the difficulty of maintaining a large supply of animals of the required age, the need for multiple, time-lapse, injections of test serums, and the attendant delay in obtaining results.
More recently a number of diagnostic methods for determining pregnancy by in vitro determination of HCG in the urine have developed. In general, these tests involve the interaction of a sample of urine to be tested with a reagent resulting in the formation or inhibition of a precipitate or a sedimentation pattern in the test vial, thus providing a qualitative indication of the presence or absence of the telltale HCG.
For example, U.S. Pat. No. 4,071,314 to Prugnaud discloses a pregnancy test of the agglutination inhibition type using lyophilized reagents including antibody sensitized particles, a buffer solution containing a calcium chelating agent, and an antiserum. Test urine is added to a tube containing the reagent and the presence or inhibition of agglutination of the particles is observed. The test is positive if agglutination is inhibited.
U.S. Pat. No. 3,579,306 to Crane discloses a test kit for pregnancy testing wherein a test tube contains dry solid pellets of red blood cells sensitized with HCG, dry pellets of antiserum, and preferably dry solid pellets of a buffer material. Urine is added to the test tube and a positive test is signified by the absence of agglutination.
In performing these and other in vitro methods of the prior art, after the test urine is supplid to a test vial, e.g., a test tube, it is necessary to maintain the test tube in an upright position undisturbed for up to two hours or more incubation. If the tube during that incubation period is jostled or shaken, either intentionally or accidentally, it will usually not be possible to complete the test; the specimen should be thrown away and the test repeated with a new diagnostic unit.